Early morning quakes rattle Chch

Christchurch has had a shaky start to the New Year. Photo / Dean Purcell

A swarm of large aftershocks which rocked Christchurch overnight and knocked out power to thousands of homes has not caused any new damage to the rattled city, authorities say.

The shaky start to what Cantabrians hoped would be a calm 2012 included a violent magnitude-5.5 quake at 5.45am felt across the region.

Geonet reported two earthquakes striking at 5.45am, just seconds apart, and of similar magnitude, which would account for the surging nature of the early-morning jolt.

It was centred 20km north-east of the port of Lyttelton at a depth of 15km and follows a similar pattern to the latest bout of aftershocks kick-started by the swarm of December 23 shakes, which included a mag-6.0.

Between 10.31pm last night, when there was a mag-3.4 shake, and 9.01am this morning, Christchurch has been rocked by a reported 14 aftershocks - all above 3.3-mag.

After the 5.45am shake, power was cut to 10,000 homes across several eastern suburbs, including Shirley, Burwood, Dallington, Richmond, and Spencerville.

A spokesman for Orion Energy said power was restored at 7.41am.

The power went down after a transformer automatically shut itself off, as it was designed to do.

A spokeswoman said: "Both Orion and Transpower have completed checks of their networks and power has been restored to the customers affected by this morning's 5.45am aftershock.

"We are now dealing with a few minor faults and should have them resolved in couple of hours."

The Canterbury Earthquake Recovery Authority (Cera) said there had not been any further significant damage.

But Cera warned on Twitter that cell phone networks were experiencing an overload and urged people to minimise their calls and texts.

Police, the Fire Service and St John Ambulance said they had not had any earthquake-related callouts this morning.

Christchurch City Council reported that a power outage in the Brooklands and Burwood areas affected a small number of pump stations but these are now operating.

The council also said water supplies were not affected, but any resident without water should contact them.

Christchurch mayor Bob Parker said the latest quakes have "rattled" residents but they needed to "remain calm, and be assured that everything was being done to ensure key services remained operational".

He said: "We have staff on stand-by ready to react quickly if the situation requires it. It's not a great start to a new year, but everyone is working hard to ensure we have a resilient and safe city in the future.

"I've heard that because several of these quakes have been offshore, some people are concerned about the possibility of a tsunami, but I'd like to reassure them that this is highly unlikely.

"The advice we have received from GNS is that the faults offshore are short in length and not likely to generate a significant tsunami. The sea inundation to land is low risk, probably not more than a storm surge."

Council facilities are being checked early this morning to make sure they can open as normal.

Anyone who is feeling distressed or overwhelmed by the aftershocks and needs extra help to cope with the situation can call the Canterbury Support Line on 0800 777 846 between 8am - 11pm seven days a week.